FT8 Operating Guide  
Weak signal HF DXing for technophiles  
by Gary Hinson ZL2iFB Version 2.37  
FT8 Operating Guide  
FT8 Operating Guide  
Recent changes to this document (just the  
stuff)  
Version  
Date  
Changes made  
2
2
2
.37  
.36  
.35  
Sept 2021 New chapter about logging (tnx for the inspiration Joe W4JF).  
June 2021 Tips on working a fox (tnx Ned AA7A).  
Mar 2021 Noted JTsync (thanks Gust ON6KE). New front graphic, courtesy of Club Log.  
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FT8 Operating Guide  
1
Introduction and purpose of this document  
1
1
1
.1  
I started compiling these notes back in July 2017 in the  
course of making over 50,000 FT8 QSOs on the HF bands,  
learning how to drive the software by using it. Some tips  
were inspired by suggestions from other FT8 users and by  
the WSJT-X developers on the WSJT-X reflector (worth  
joining). Many address Frequently Asked Questions and  
draw on my 40-odd years of HF DXing … some very odd.  
Some of my tips (such as split  
operating, tail-ending and using  
low power) are contentious and  
not universally adopted by FT8  
users – and that’s fine. To an  
extent, we are figuring this stuff  
out for ourselves as we go along,  
which for me is all part of the fun.  
These tips work for me. Your  
situation and preferences may  
.2  
.3  
That said, these are just tips, pragmatic suggestions aimed  
at making FT8 easier and more effective to use on the HF  
bands. They are not rules or laws! It’s only a hobby! The  
digital modes, protocols and programs are being actively  
developed, while the operating conventions or habits on-  
air are still evolving. Other approaches may be even better me know if they work better. ꢀ  
than those I suggest here … and that’s cool.  
vary.  
By all means try out  
different approaches … and do let  
In particular, I must point out that I am a keen HF  
DXer with zero experience using FT8 intentionally  
for meteor/rain/aircraft scatter, EME, topband and  
VLF, 6m and up etc. I have only used FT8 on 80  
through 10 metres. Hopefully much of the advice  
here is useful in other contexts (e.g. topband  
DXing) but different techniques may well be  
appropriate and necessary, in which case please  
I am primarily a Microsoft Windows  
sufferer user. WSJT-X is an impressive  
example of multi-platform coding that  
works on Linux, MacOS, Windows (XP and  
up) and other platforms, with only minor  
differences … but since I only run it on  
Windows 8.1, please don’t pelt me with  
rotten tomatoes if things don’t quite work  
look elsewhere for guidance. Likewise for other  
modes such as JT9 and MSK144.  
as described on your system.  
RTFM! Seriously, please study the docs! The FT8 software installation instructions, online user guide,  
built-in help and tooltip popups will help you install, configure and start using the software with your  
computer and rig. Most initial issues, problems and queries are answered therein, plus there are  
useful tips. This “Operating Guide” is intended to help you get the best out of FT8 from an  
operational perspective after you have it up and running. If you still have issues after all that, please  
search the online support forum (reflector) archives  and finally feel free to ask for help on the  
reflector. The developers are focused on designing, developing and refining the protocols so please  
have some consideration: basic queries answered elsewhere are likely to remain unanswered.  
Important disclaimer  
We are all individually responsible and indeed accountable for complying with our  
licenses plus applicable laws, regulations and conventions that may, for instance,  
specify permitted powers, modes, bands/frequencies (e.g. on 60m) and bandwidths,  
or impose obligations concerning remote operation, on-air identification and logging.  
Just because the software allows us to do something does not necessarily mean it is  
legal and appropriate for us to do so. Neither the development teams, nor the author  
of this guide, are responsible for your compliance. You are, dear reader!  
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FT8 Operating Guide  
2
START HERE  
2
.1  
Use the latest available release of the FT8 software. You have a few program choices:  
WSJT-X was written by the team that invented the mode (the daddies, you might say!). In the  
best tradition of amateur radio, WSJT-X is open-source, hence others are developing variants  
(
derivatives) of the program, changing the user interface and in some cases meddling with the  
JTDX by Igor UA3DJY and team is a stable, usable variant with several helpful tweaks to the user  
interface. It is similar enough to be familiar to anyone who already knows WSJT-X. Although  
sadly the official JTDX documentation is woefully out of date, see Appendix D for tips on using  
The user interface in MSHV by Christo LZ1HV is a little different. MSHV enables semi-rare DX  
stations to make several QSOs in parallel using the regular FT8 protocol (not fox-n-hounds  
DXpedition mode  more hunt saboteur mode) … at the cost of increased transmit bandwidth  
higher band occupancy) and less power per signal. The multi-QSO facility does not work in  
contest mode (thankfully!) and should not be used in the normal FT8 sub-bands, please.  
JS8call by Jordan KN4CRD is a derivative that re-purposes the core FT8 digital transmission  
protocol to enable longer free-text messages to be exchanged. This allows a more  
conversational style of QSOs at the same leisurely rate of about 5 words per minute. As with  
plain FT8 and in contrast to CW, RTTY and PSK, messages are sent blockwise as heavily-  
compressed messages, not as individual characters. IT REMINDS ME OF TELEX <STOP> Or  
Twitter. Or simplex traffic handling <OVER>  
Logging programs (such as Logger32 and N1MM+) can interface to FT8 programs, effectively  
using them as intelligent soft modems. Maybe one day the loggers will take over the  
sequencing, highlighting etc. leaving just the message coding and decoding to the modems, but  
for now the programs interface to share tasks such as logging completed QSOs.  
2
.2  
Software updates are frequent with all variants as bugs  
and flaws are discovered and fixed, and new functions  
Aside from ‘alpha’, ‘beta’ and  
production’ there are other,  
roughly equivalent terms. WSJT-X  
are released for alpha or beta testing.  
If  
imperfect/incomplete software makes your blood boil,  
give FT8 a wide  
has its ‘Release Candidates’ and  
General Availability’ versions. JTDX  
It’s worth checking from time  
to time for new versions of the  
berth and keep your  
cool. If you prefer  
uses ‘Evaluation versions’, ‘Step  
releases’ and ‘General releases’.  
software and this guide. Make  
reasonably stable  
it part of your routine e.g. at  
and reliable software, stick with the production releases,  
avoiding the betas and definitely the alphas.  
the start of the month, and/or  
keep an eye on social media.  
Please, read it. Study it. Ingest it. Memorize it.  
Banish dumb questions! Be like FT8 boss!  
This advice stands even if you use JTDX.  
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FT8 Operating Guide  
2
2
.3  
.4  
With your chosen software running, press F1 and study the help file/manual. The WSJT-X help is  
well written, if I say so myself. You’ll discover, for instance, that the confusing combinations of  
shift, alt or control keys and clicks are handily explained on the screen by pressing F5 to “Display  
special mouse commands”. By far the most useful combination in WSJT-X is to shift-click on the  
waterfall to put your transmitted signal there (think of it as ‘shift my Tx). If nothing else sticks  
from these notes, at least remember to shift-click … or right click in JTDX.  
Although not yet shown on the pop-up help, we can also right-click on the WSJT-X waterfall and  
1
then click the only option to set both Rx and Tx frequencies right there .  
From time to time, check for  
updates to the digimode software,  
as you should for all the other  
software on your system. Most  
applications, operating systems  
and drivers are updated or  
patched occasionally, addressing  
bugs and flaws or adding new  
facilities (potentially including  
changes to the FT8 protocol itself).  
WSJT-X does not automate this for  
New releases are  
reflector and the news soon  
percolates through other ham  
radio forums, plus on-air of course.  
It’s much the same with JTDX and  
MSHV: join the online communities or monitor the authors’ websites to keep up with  
developments.  
1
Why we can’t simply left-click to move the Rx and right-click to move the Tx in WSJT-X is beyond me. Much more intuitive …  
and that approach works perfectly well in JTDX.  
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FT8 Operating Guide  
3
Important: accurate timing  
3
.1  
Check your computer’s clock. Accurate timing is quite  
important for FT8: if your computer clock is wrong by more  
than a second or so, you will probably experience problems  
e.g. few responses to your CQs and being ignored whenever  
you call others.  
If you see plenty of FT8  
signals on the waterfall but  
few decodes, blobs that cross  
the horizontal tramlines on  
the waterfall and/or a distinct  
bias in the DT values on the  
decode, those are all strong  
clues that your computer’s  
clock may need resetting.  
Note: despite what some may claim, extreme millisecond  
accuracy is NOT required. FT8 signals contain distinctive  
synchronisation sequences that the receiving systems use to  
identify the data portions in the received audio stream.  
Accuracy to within a second is plenty good enough in practice.  
If your computer is Internet-connected, it’s easy to check the clock by browsing to the Time.is  
3
.2  
JTDX displays a rolling average of the DT values (delta time i.e. how many seconds each message  
is offset relative to the expected start and finish times according to the system clock) and two Lag  
values (i.e. how many seconds into  
the start of the next period it took  
your computer to decode the  
messages shown, followed by the  
count of messages decoded) in  
Band Activity header area (if wide  
enough) ►  
On a busy band, if everyone else seems to be a bit early or late, chances are that your own clock is  
wrong. An average DT value between minus 1 and plus 1 is fine in practice since JTDX can still  
decode reliably even with DT of 2 seconds (e.g. if a DX station’s clock is a second fast while your  
clock is running a second slow). If your average DT is more than ±1, adjust your clock.  
The Lag values indicate whether your computer has enough processing power. QRP computers  
struggle to decode all the messages on a busy band, especially if you have configured the software  
to dig deep into the noise for every last scrap of information. Conversely, QRO computers cope  
easily and quickly with all the signal processing required, without intruding very far (if at all) into  
the next period. So, if you see large lags and often notice late decodes appearing after you have  
started transmitting a message, it may be time to fiddle with the software settings, close down  
other programs to conserve resources for FT8, or consider upgrading your trusty old difference  
engine or steam-powered abacus to something more modern, more this-century.  
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FT8 Operating Guide  
3
.3  
Manually adjusting your system clock soon becomes annoying, trust me. There are better ways.  
For starters, pop open the computer lid and check/replace the button-cell battery that should keep  
the real time clock running even when the PC is powered down. Provided you have Internet access,  
the free Meinberg NTP software maintains clock accuracy, initially by synchronising your PC time  
to reference time servers on the Internet using Network Time Protocol designed for that purpose,  
and then micro-adjusting the clocks tick rate to remain synchronised (rather than just periodically  
resetting the clock, which is the more common but cruder approach). Install, configure, check,  
others, each with their fans.  
3
.4  
Recent versions of Windows Server and Windows 10 offer an updated W32Time time service called  
stopped, configured and queried from an elevated command prompt e.g.  
C:\> w32tm /config /update /manualpeerlist:pool.ntp.org,0x1  
where:  
/config means we are reconfiguring the W32tm Windows time service  
/update means apply the config changes to the service  
/manualpeerlist: means we want to specify NTP time servers other than the Windows default  
server time.windows.com  
pool.ntp.org tells the system to choose a nearby time server from the global pool. There are  
several regional pools (e.g. oceania.pool.ntp.org) and country pools (e.g. nz.pool.ntp.org) or  
you can name one or more specific time servers instead (separate their addresses with commas)  
,0x1 is a flag meaning use the ‘special poll interval’ for this server, where ‘special poll interval’  
is a fixed value in seconds defined in the registry under this key:  
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient  
e.g. a SpecialPollInterval of 600 decimal means poll the time server every 10 minutes.  
If you are unconcerned about the accuracy of your clock but simply want to work  
someone with timing issues, you can deliberately nudge your clock forward or  
backward manually. You may notice their blobs don’t line up with the horizontal  
timing lines on the waterfall, as in this example  YD3BGM’s messages were decoded  
OK  with an uncorrected DT of -2.4 seconds (i.e. he was transmitting 2.4 seconds  
early, relative to my computer  
clock). On the headphones, I  
heard his tones starting well  
before other stations using  
the same timeslots. First I  
called him several times without success,  
despite the path being wide open between  
us.  
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FT8 Operating Guide  
Guessing that he might be using software with less tolerance on timing, I  
clicked to open the Windows system clock  opened the change date  
and time settings function, clicked the Change date and time button,  
clicked the seconds part of the digital clock, clicked the up arrow 2 or 3  
times to advance my clock by about 2 or 3 seconds (deliberately making  
my system clock inaccurate!), then clicked OK to set the clock. After  
checking the decodes to confirm that his DT was reduced to just 0.2  
seconds, I responded to his CQ call again and this time we completed a  
QSO easily. I closed with a free-text message “CHK UR CLOCK” … which  
he evidently did a few minutes later. Meanwhile I had reset my own  
system clock until the time.is website showed it was within a second of the  
correct time. Meinberg NTP (which I simply left running throughout the  
process) adjusts the clock rate to correct it gradually from there and  
maintains millisecond accuracy until the next time I run into the same  
situation.  
Tip: to move his  
blobs up the  
waterfall, click  
the up arrow.  
3
.5  
From time to time, the FTn reflectors suffer zombie  
If you are offline (perhaps clinging  
precariously to a mountain peak on a  
SOTA expedition, or on a remote IOTA  
DXpedition), you can use a GPS  
receiver or radio time standards such  
as WWV to check and adjust the  
computer clock. Even a reasonably  
accurate quartz watch will do provided  
it was recently checked against a  
reliable time reference before you set  
out. Alternatively, simply listen to the  
FT8 signals on a lively band to figure  
out when most of them start and stop:  
that’s your cue to set your clock.  
outbreaks whenever someone naively asks what is the  
best way to set their system time, or suggests some  
other way to meddle with the time settings. GPS  
pucks, Rasperry Pies, WWV, mean(DT), clock-nudgers  
and other such ideas have all come up, repeatedly,  
been kicked around for a while before eventually  
slipping back to the graveyard … until the next  
outbreak. For all home-based hams, any suggestion  
not involving a definitive time reference is  
fundamentally unsound. Those involving atomic  
clocks may be viable  but are generally trumped by  
Use an NTP time server from the pool” if you are  
Internet-connected, or “Use GPS” if not. How to do  
that is simply a matter of personal choice. There is  
[
Thanks Rod YJ8RN for the tip]  
These modes are not designed for long conversations or ragchewing. Rather  
they concentrate on efficient exchange of such basic information as call signs,  
Maidenhead grid locators, signal reports, and acknowledgements at the  
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FT8 Operating Guide  
4
Important: transmit levels  
4
.1  
Although FT8 is a constant-carrier FSK  
mode (unlike PSK, CW and SSB),  
overdriving will distort and widen your  
signal (making it less likely to decode)  
and may generate spurii. Set the  
transmit levels so that the entire chain  
from AF generation through to RF  
transmission is operating linearly.  
Check out your transceiver, sound system and  
software on-air on a quiet frequency with a  
competent ham giving you honest feedback, or while  
monitoring your own transmissions on a Web SDR as  
you systematically adjust the settings and make  
notes. Beware, though, that web SDRs can be  
overloaded by strong signals, so don’t.  
4
.2  
If you set your transmit levels as badly as the FT8 station ringed in red on the left  you may  
unknowingly be generating ‘ghostly barcodes’ (in the 3 dotted rings): despite looking like some  
obscure new digimode, these are audio harmonics caused by generating too much audio output  
from the PC sound card which overloads the audio input circuits in the radio: [Tnx tip Bill G4WJS].  
4
4
.3  
.4  
Setting your transmit levels is a bit more complicated than it seems: simply adjusting the rig’s  
power output control is not sufficient as even QRP signals can be rotten if the rig’s audio is  
overloaded and distorted.  
Take care adjusting the audio output level from the sound  
card and audio input level to the rig: consult your radio  
manual to find out how to set the audio drive level  
properly. On some rigs, the ALC meter is, in effect, a  
distortion meter: any non-zero ALC indication is bad news.  
On rigs that use ALC to control the power output  
Sorry I can’t be more specific here.  
If you are unsure, err on the side  
of caution: keep your PC audio  
output level low, just enough  
drive to generate some RF output  
(you don’t need much!).  
(e.g. Icoms), high ALC indication is normal at QRP levels, so  
it’s not much help for setting the audio input.  
On the Elecraft K3, set the PC sound card  
output (using the sound card headphone  
level slider and/or the “Pwr” slider on the  
WSJT-X/JTDX main window) and the K3’s line  
input level (confusingly, using the front panel  
MIC” control in DATA mode) to indicate 4  
blobs on the ALC meter with a flickering fifth  
blob indicating the onset of ALC action ►  
Listen to your transmitted audio using the rig’s monitor function – maybe not all the  
time but it pays to listen occasionally just in case, for some reason, you are  
transmitting distorted audio, PC bleeps, DX announcements, wideband noise, coughs  
or whatever. Watch your power meter too for clues that something might be amiss.  
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FT8 Operating Guide  
The Spinal Tap approach, also known as Mediterranean  
Syndrome (“All knobs to 11”) will create more mayhem and  
complaints than FT8 QSOs. Resist the urge.  
With many FT8 stations using QRP, someone running,  
say, 100 watts or more stands out from the crowd …  
but not in a good way, especially if they are not hearing  
callers. Similarly, those running 50 watts to large  
beams on a wide-open band: that’s a lot more ERP than  
most FT8ers. However, QRO may well be necessary  
and appropriate on marginal paths.  
Automatically report callsigns and  
Aside from QRO being antisocial and usually reports to PSK Reporter by selecting  
unnecessary, if your signal is too strong, it may be dirty F2 Settings  Reporting  Network  
and may overload receivers and audio cards at the DX Services  Enable PSK Reporter  
end, preventing your signal from decoding reliably. Spotting. On the PSK reporter map, if  
Take your cue from the signal reports you receive: if you others receive you much stronger  
are getting positive reports, you can probably do just as than you receive them, your receive  
well (maybe even better) with a fraction of the power. capabilities need some attention,  
Remember: decibels are logarithmic. Cutting your and/or you may be running excess  
4
.5  
power in half will reduce average reports by just 3 dB;  
cut it by half again to lose another 3 dB, and so on. If  
you are receiving mostly negative  
or zero reports, you are in the  
power. [Tnx tip Martin G0HDB]  
right region. I normally adjust  
my transmit power to get  
reports between 0 and -10 dB.  
If you receive a 58 report but  
you’re not using SSB, something  
may be seriously amiss!  
4
.6  
If you are routing transmit audio  
from the sound card to the front-panel microphone input on the rig, be sure to turn off the radio’s  
speech processor and any audio shaping/profiling when using digimodes to avoid distorting your  
signal. Radios with a rear-panel line-level input especially for digimodes, or a special ‘data’ mode  
that automatically disables the processing (such as the K3), tend not to suffer issue. [Thanks for  
the tip Joe W4TV]  
Take care not to exceed your radio’s rated power output for digital modes.  
Each FT8 over lasts 15 seconds. Transmitting at 100% duty cycle for 15 seconds  
may cook your finals, especially on bands or antennas where the PA is less  
efficient. Check the radio manual for advice  seriously, read the manual.  
Listen for additional fan noise. Feel the radio case for excess heat. If you smell  
smoke, you’ll wish you had paid attention to this issue before it escaped.  
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FT8 Operating Guide  
4
.7  
Although FT8 is a weak signal mode, not a QRP mode  
per se, please keep your transmit power down. Be  
nice! Generally on HF, if a path is open, just a few  
watts will do. Put your amplifier on standby. Turn  
down the wick to QRP levels. Try it! If you don’t get  
any responses at all, try 10 watts, maybe 20 or 30. If  
you find that you routinely ‘need’ 100 watts or more,  
that is a strong hint that your feeder and antenna  
system are inefficient, or you are flogging dead bands.  
Check for corrosion and loose connectors. Try making  
a simple halfwave dipole as a comparison antenna.  
You will find that you can receive better if your  
antenna is in good shape, and  trust me  good  
reception is kinda useful for DXin.  
There are situations where QRO, up to  
your license limit, is both appropriate  
and necessary, for instance CQing on a  
closed band, hoping to catch DX as the  
band opens, or calling someone weak  
(
below, say, -20 dB). Occasionally, we  
experience one-way propagation as if  
there is giant diode in the  
a
ionosphere: DX stations are loud but  
cannot hear us. Maybe they have high  
QRM their end. Maybe there is a tilt in  
the ionosphere. Maybe they have  
badly designed or operated systems.  
4
.8  
Near the low end of the range, Signal-to-Noise Ratios  
“All SNR values from the decoder limit  
are of dubious value due to how they are calculated  down to minus infinity lie just below  
the decoder threshold and estimates  
of SNR near that threshold can have  
huge variance despite only being a  
few percent different in signal  
strength. The WSJT-X decoders limit  
these potential outlier estimates to  
an artificial floor which is known to be  
just below the lowest possible true  
The SNR figures compare the strength of the signal (50  
Hz wide in the case of FT8) to the noise across the 2½  
kHz bandwidth typical of an amateur SSB receiver:  
that’s 50 times the signal bandwidth (17 dB). So a -17  
dB SNR FT8 signal is on a par with the noise, making it  
virtually inaudible. For comparison, CW is copiable by  
SNR value achievable from the mode  
as determined by rigorous application  
of information theory.”  
[
Tnx Bill G4WJS]  
The cough gauge ►  
I also noticed by accident that when I cough  
the gauge goes up into the red.”  
Ah, that’ll be because your PC microphone is  
active. Try selecting the soundcard input from  
your rig. Or dose-up on cough syrup.  
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FT8 Operating Guide  
5
Important: receive levels  
5
.1  
The bar graph audio level meter in WSJT-X or JTDX should normally  
read about 30 dB on a dead band, increasing to about 50 dB on an  
active band with about a dozen stations QRV simultaneously, higher  
still on an HF band buzzing with life and lots of strong FT8 signals. If  
the level goes too high and turns red, you are reaching the  
compression point in your sound  
The bar graph bar should card and may be over-driving it,  
normally  
showing  
be  
green, causing distortion and sampling  
acceptable errors in the ADC (Analogue to  
The audio level bar  
levels. If it turns red, Digital Converter) that, in turn,  
there’s too much or too reduce the ability to decode FT8  
graph reminds me of  
Star Trek’s medical bay  
little received audio.  
signals. You might even damage  
your sound card.  
5
.2  
Here’s how to set the audio input level to WSJT-X or JTDX on a  
Windows system, step-by-step:  
1
2
. Right-click the Windows loudspeaker icon at the bottom right  
corner of your main screen and select Recording devices ►  
. Select the sound card input that receives audio from your radio  
(preferably a “line” input if there is one on that sound card,  
otherwise the “microphone” input) then click Properties  
3
4
. Select the Levels tab and set the slider near the middle  
of the range. Hopefully it is most linear in this region.  
Trust me, it doesn’t need to be precisely in the middle.  
. If there is a balance control, set both audio channels to  
the same level. On a radio with dual-receivers feeding  
the left and right channels on a stereo output, or with  
two radios, you may want to monitor each channel  
separately with two instances of WSJT-X or JTDX, for  
example monitoring FT8 and WSPR simultaneously.  
5
. Click OK to close the Levels tab, then  
open the Advanced tab . Check that  
the default format is 48000 Hz (DVD  
Quality), the preferred sampling rate  
for WSJT-X and JTDX. The default  
default rate is often 44100 Hz (CD  
Quality): converting that to 48000 Hz  
wastes CPU cycles, creates resampling  
errors and degrades decoding - best  
avoided if 48000 Hz is available and  
works on your system (it may not). 16  
bits are sufficient: more is OK.  
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FT8 Operating Guide  
6
7
. Click OK and OK again to exit the Windows sound settings.  
2
. Launch WSJT-X if it is not already running . With your  
Clap your hands or shout out: if  
you see the bar graph level flick  
up, you may have selected the  
PC’s microphone rather than the  
radio input! Oops. Easily done.  
radio OFF, check the bar graph at the bottom left corner  
of WSJT-X main screen. The level should be at or near  
zero, flickering red. There may be a few dBs of noise  
generated in your sound card, or a little stray pickup on  
its input (e.g. some AC hum if it is poorly shielded). If  
you see a lot of input, something is wrong. Check that you have selected the radio audio input  
to WSJT-X under F2 Settings  Audio. The input should show the sound card line or  
microphone input from the radio that you checked/adjusted above.  
8
. Now turn ON your radio and tune to a quiet  
In contrast to VHF/UHF, there are  
band, with the attenuator off, RF gain up high  
usually lots of strong FT8 signals on the  
HF bands at peak times: “weak” HF DX  
signals are generally only weak relative  
to other HF signals, rather than weak in  
absolute terms relative to the noise  
floor, so strong signal handling and  
and preamp set as normal. You should hear just  
a little background noise on the radio - band  
noise plus noise generated in the receiver  
itself. The bar graph in WSJT-X should be read  
about 30 dB. You may need to adjust the audio  
output level from the radio (the Line Out level if  
dynamic range tends to be more  
you have that facility, otherwise the AF level) and  
important than sensitivity on HF.  
until WSJT-X shows about 30 dB.  
9
. If your radio has a fixed (non-adjustable) line level output or one  
It might be worth  
comparing different  
USB ports for your  
USB sound system or  
that cannot be reduced to about 30 dB on a dead band, have you  
plugged the radio line output into the microphone socket on the  
PC sound card by mistake? Or have you selected the microphone  
input rather than the line input on the sound card? Check the  
labels on the sound card inputs and the sound card settings. If  
there is no “line in” but only a “microphone” input, and no way to  
turn off the microphone preamplifier in the sound card settings,  
you might need an external attenuator (e.g. a potentiometer) in  
rig connection: some  
are noisier than  
others in my  
experience.  
the audio lead from your radio to reduce the audio level feeding  
into your PC sound card, or you may need to use the radio’s headphone output rather than  
the line out, using the radio’s AF gain control to set the quiescent level on the WSJT-X bar  
graph to (yes, you guessed it) about 30 dB.  
1
0. Now tune to band that has some life in it, using  
If there is so much band activity that  
the band selector on the WSJT-X main  
the bar graph is near the top of the  
screen. You should hear FT8 signals on the radio  
scale and turning red, turn off the  
and see signal blobs on the waterfall. The WSJT-  
radio’s preamp, turn on the attenuator  
3
X bar graph should read about 40 to 70 dB , still  
and/or reduce the RF gain to bring the  
in the green, and after a period or two you should  
levels back down to the green zone.  
see some decodes appear.  
That’s it, you’re done! To avoid having to repeat this whole process, you might like to make some  
notes about the settings though, just in case ‘someone’ fiddles with ‘something’.  
2
If your radio has a built-in sound card and USB interface, you won’t be able to use the sound card while the radio is switched  
off  but to simulate no audio input, maybe you can tune to a dead band and disconnect your antenna? [Tnx tip VE3AND]  
3
The dB values here are decibels relative to a reference level, the digitized signal value 0001.  
Copyright © 2021 ZL2iFB  
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FT8 Operating Guide  
5
.3  
Even having set up your receive levels carefully, and if you  
are using a high quality modern rig with a high dynamic  
range, particularly strong signals often appear wider than  
others … but don’t be too quick to blame it on someone  
running excessive power and splattering. They may be  
locals, and if they are DX it could just be that the path  
happens to be wide open between you.  
When conditions are favourable,  
I’ve often seen genuine QRP DX  
signals showing plenty of red on my  
waterfall.  
Remember, FT8 is  
designed for weak signal DXing.  
The yellow fuzz either side of a solid red blob like this is probably just  
a display artifact i.e. low-level skirts on the digital filter that generates  
and colours the waterfall. Despite appearances, most FT8 signals are  
clean in fact. That said, I would avoid CQing close to a strong signal like  
this (in the fuzzies), even if I chose to  
More tips about using your  
transmit at the same time as him.  
There are generally better places elsewhere.  
filters and AGC below.  
FT8 Operating Guide  
6
Other software settings  
FT8  
FT4  
None  
3.575  
None  
7.0475  
10.14  
14.08  
JT9  
1.839  
3.572  
None  
7.078  
10.14  
14.078  
4
1.84  
6
6
6
.1  
Preferred frequencies for digimodes are normally expressed as  
VFO “dial” frequencies in megahertz, with the radio set to USB  
or DATA mode  The actual transmit frequency is higher by the  
audio frequency according to where the red Tx goalposts sit  
above the waterfall.  
3
5
7
.573  
.357  
.074  
1
1
0.136  
4.074  
.2  
.3  
Dial frequencies for various modes can be checked and  
customised through the F2 Settings  Frequencies tab. If you  
make a mess of the settings, right-click the table and select  
1
8.1  
1.074  
4.915 24.919 24.919  
8.074 28.18 28.078  
18.104 18.104  
21.14 21.078  
2
2
2
Reset’ to recall all the default frequencies for all the supported  
modes.  
In order to avoid your transmit frequency continually jumping or being pulled around by successive  
callers, in WSJT-X, select (tick, check) the Hold Tx Freq option; in JTDX, click the yellow Lockd TX=RX  
button to turn it to green Tx/Rx Split. Even with Hold Tx  
Freq or Tx/Rx Split selected, you can still put your Tx  
where you want by shift-clicking the WSJT-X waterfall or  
right-clicking the JTDX waterfall, and you can call someone  
on their frequency (simplex) if you really must: simply hold  
Ctrl as you double-click their CQ message, or shift-  
click/right-click your Tx to their frequency, or click the up-  
arrow button to move your Tx frequency. It’s seldom a  
good idea though, especially if you are calling a rare DX  
station. Their frequency tends to get busy with callers.  
6
.4  
Pick a readable font type and size under F2 Settings  
General tab, particularly for the decodes. Personally, I  
prefer sans serif fonts with a slashed zero such as Monaco  
or Consolas . Your monitors, eyes and preferences may  
vary, so fiddle with the fonts and font sizes until you’re  
happy. FT8 is an experimental mode after all!  
The watchdog (WD) timer is a vigilance  
It's not goo
control, a kind of dead-man’s handle. If  
while transmitting the operator appears to  
have dozed-off for a defined period, the  
trusty automatic watchdog springs to life,  
shutting off transmissions that would  
otherwise continue indefinitely, displaying  
a red warning message. There are two  
things you can do to stop this:  
without a break: I recommend taking a breather  
after 5 or 6 minutes max. The WD timer counts  
down in the bottom right corner of the main  
window. When the time is up and the Tx  
disables, it’s worth checking that your transmit  
frequency remains clear of QRM at the times you  
would be transmitting. In fact, it’s not a bad idea  
to QSY anyway since you may be QRMed by  
someone too weak to see (hence the lack of  
response to your CQs or calls), or perhaps  
coincidentally they have been bitten by their  
watchdog at the same moment as you!  
1
. Kick the watchdog! A click anywhere in  
the window (even between the buttons)  
tells the watchdog you are still awake and  
unexpired, resetting its countdown timer.  
4
6
0m frequencies vary around the world: check your license and local bandplan for details.  
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FT8 Operating Guide  
2
. Give yourself more time. You’ll find the starting value for the countdown under F2 Settings then  
General for both Tx watchdog and Tune ▼  
6
6
.6  
.7  
In DXpedition mode with WSJT-X, the hounds watchdog timers are fixed  
at 3 minutes. After calling the fox 6 times, our transmitters are  
automatically disabled if we haven’t had a reply. We can simply click  
enable Tx to continue calling the fox … but it’s a good idea, first, to take a  
moment to check that our Tx frequency remains clear during the even  
periods when we would be transmitting.  
We are more  
likely to be heard  
by the fox on a  
clear frequency.  
This is DXing 101.  
Select Auto Seq. Auto-sequencing works quite well  
“The auto sequencer is doing the  
with FT8, reduces operator stress and cuts down on  
newbie operating errors (e.g. not selecting the next  
message in time, not the correct one anyway). If  
Auto Seq gets it wrong, you can override the auto-  
selected message by quickly clicking the Tx message  
button for your choice of message. If you do this  
during the first few seconds of your transmission  
equivalent of double-clicking each  
response from your QSO partner ... A  
QSO will be ‘correctly’ sequenced by  
double-clicking each of your QSO  
partner's responses as they arrive. This  
is how you would normally use the  
application in modes without auto-  
sequencing like JT9 and JT65 although, of  
course, you can click through the next  
message manually as well: automation is  
an aid not a necessity.” [tnx Bill, G4WJS]  
(
during the synchronisation segment), the revised  
message will probably be sent as intended. If you  
arent quick enough, the message may be corrupted.  
Alternatively, there’s the 100% manual option ►  
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FT8 Operating Guide  
6
.8  
If you inadvertently select one of the Contest options under F2  
Settings  Advanced in WSJT-X you will be perplexed to  
discover weirdness in your generated messages and  
sequences▼  
Stop tinkering with random  
settings or you’ll be sent to  
the naughty step!  
5
Deselect (un-tick) Special operating activity to resume normality.  
5
JTDX does not support contests.  
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FT8 Operating Guide  
7
How to respond to a CQ, or call a specific station  
7
.1  
First set things up:  
Set up WSJT-X or JTDX to control the rig using CAT.  
Set the receive and transmit audio levels and the rig’s power level correctly.  
Find a clear slot  
on the waterfall  
and shift-click  
(
WSJT-X)  
right-click (JTDX)  
to set your  
transmit  
frequency there.  
Enable/select  
Auto Seq and  
Hold Tx Freq.  
Check the WSJT-  
X
F2 Settings  
General and  
select Double-  
click on call sets  
Tx enable ►  
Show DXCC entity  
and worked before  
status  
decoded  
highlights  
CQ  
messages that are  
new ones for you on the Band activity pane.  
Double-click on call sets Tx enable makes it dead easy to respond to a standard CQ message: when  
you double-click a decoded message, WSJT-X does several things for you:  
It puts the other station’s callsign and gridsquare (if they sent one)  
into the DX Call and DX Grid boxes on the main window, displaying  
the short path beam heading (if they sent a grid).  
Select Tx messages  
to Rx frequency  
window to see your  
outbound and  
inbound messages  
in contrasting  
background colours  
show this.  
It generates the standard messages you will send, with their callsign  
and your report to them inserted.  
It selects the appropriate transmit periods, even or odd, the opposite  
of whichever periods the DX station is using.  
It copies the decode you clicked to the bottom of the Rx frequency  
pane on the right.  
It selects message Tx 1.  
and finally …  
It sets Tx Enable so you will start transmitting when it’s your turn.  
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FT8 Operating Guide  
7
.2  
Before you double-click a decode to call someone, select a suitable transmit frequency. Shift-click  
(WSJT-X) or right-click (JTDX) on a clear space on the waterfall to put the red goalpost there.  
The CQing station doesn’t need to say up 3 or anything else. He will decode all stations in the  
audio spectrum. You can call him at 300Hz or 2300Hz and it won’t make any difference. They  
all display. You don’t have to (and don’t want to) move to his frequency. If there is more than  
one station calling him, they will hopefully be spread all over the audio spectrum, not causing  
QRM to the station trying to make a QSO or each other. If a bunch call on his frequency, they  
just QRM each other and the guy CQing will be working those who are split. Additionally, if he  
starts a QSO with someone close to your transmit frequency, your transmitter will be disabled  
so you don’t cause him QRM. If you are transmitting further away, you can keep calling him and  
he should pick you up as he works through the list of callers.” [Tnx Gary AG0N]  
Three strategies for picking your Tx frequency  
1
. The easy approach is to pick a clear frequency (i.e. a blank column on the waterfall) and hope  
it is also clear for those you want to contact. This strategy works well on a quiet band but is  
less effective when the band is chockablock. There may be no blank columns! A less-busy  
frequency may be your only option e.g. partially overlapping one or two other stations, or  
somewhere near the left or right sides of the waterfall (although the DX station’s filters may  
cut off more sharply than yours).  
2
3
. If the DX station doesn't appear to copy you at all for a few transmissions, move to a different  
transmit frequency. Likewise, if a QSO appears to stall, the DX station repeating the same  
message to you several times … eventually giving up on you to work someone else.  
. Avoid calling ‘simplex’ on the same frequency as a DX station, except as a last resort. Naïve  
FT8 users tend to call ‘simplex’, QRMing each other in much the same way as a pileup on the  
legacy modes. The rarer the DX, the worst this problem becomes. He will struggle to copy  
anyone reliably, unless by chance most stop calling and the frequency goes quiet.  
[
Tnx Jeff, WA1HCO]  
7
.3  
You can call anyone you like … but you’ll find it more productive  
to call stations you can actually copy, at the right moment.  
There is a silent DE in most  
messages. “S9A ZL2iFB RF80”  
means “S9A DE ZL2iFB RF80”.  
Stations you can actually copy’ are the ones sending the  
second callsigns in messages containing two callsigns e.g.  
S9A ZL2iFB RF80  
ZL2IFB S9A JJ30  
ZL2IFB S9A -23  
ZL2IFB S9A RR73  
TNX TIPS GARY  
These messages  
were all sent  
by ZL2iFB:  
These messages  
were all sent  
S9A ZL2iFB -21  
S9A ZL2iFB RR73  
TNX NEW 1 73  
by S9A:  
If you intend to call S9A, the best way is to browse through the lefthand Band Activity pane to find  
a standard message sent by S9A (i.e. one with some other callsign first, then S9A, ending with a  
locator, signal report or RR73 message) and double-click that. Your system will normally start  
calling him at the start of his next listening period. If he is in QSO with someone, your transmission  
may be sent at the same time as the station he is working … which may cause QRM unless you are  
transmitting on a clear frequency (hence the previous advice). If not, quickly click Halt Tx to stop  
transmitting and wait until the QSO is over before clicking Enable Tx to start calling.  
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